There are current sensors which measure an electrical current through an electrical conductor. The current in this case generates a magnetic field, and the current sensor measures this magnetic field and deduces the strength of the current.
In this case, the exact position of the current sensor (or of the sensor elements of the current sensor) with respect to the electrical conductor is critical: as the magnetic field of the current conductor is highly inhomogeneous, even a minor position change of the current sensor can greatly influence or modify the magnetic field on the sensor elements.
Current sensors are known in which the electrical conductor is an integral component of the sensor housing. The conductor and the current sensor are therefore located at a fixed spatial distance from one another. The producer of the current sensor undertakes the calibration, i.e. the positioning of the sensor element in relation to the electrical conductor.
Furthermore, current sensors are known in which the electrical conductor is not a component of the sensor housing. Such current sensors have a sensor housing which, for example, is fastened on the electrical conductor by a customer. Because of tolerances in the fastening, however, it often occurs that the sensor element does not exactly detect the desired magnetic field, but instead a magnetic field differing therefrom. This leads to an error in the current measurement which may for example lie in a range of from 5% to 15%. This is disadvantageous when a higher accuracy of the current measurement is required, in particular an error of at most 1%.
DE 10 2012 110 406 A1 discloses a proposal for current measurement, in which the current sensor comprises two types of sensor elements (for example Hall plates and vertical Hall sensors). The first type of sensor detects a magnetic field component perpendicular to a conductor surface, and the second type of sensor detects a magnetic field component parallel to the same conductor surface. If the relative magnetic sensitivity of the two sensor types with respect to one another is know, the position of the sensor elements can be deduced with high accuracy from the ratio of the two measurement values, and accurate calibration of the current sensor is therefore achieved.
In this case, however, it is a problem that two different types of sensors are required, for which, for example for technological reasons, the relative magnetic sensitivity with respect to one another cannot be known sufficiently accurately. With different types of sensors, for example, different process variances or individual variances of the sensors may occur, which require additional compensation measures (so-called trimming procedures). Without such compensation measures, the ratio of the magnetic sensitivities on the chip is only known to 1±4%. This leads, for example, to an uncertainty of the order of 8% (tolerance band), which results for example because of variances of layer thicknesses, different doping concentrations, different outward diffusion and/or different influences of mechanical stresses on the two sensor elements.